Email is also one of the series datatypes, so the same rules that apply to series apply to emails:

probe head change/part jane@doe.dom "john" 4
john@doe.dom

Format

The standard format of an email address is a name, followed by an at sign (@), followed by a domain. An email address can be of any length, but must not include any of restricted characters, such as square brackets, quotes, braces, spaces, newlines, etc..